Facebook CEO Mark Zuckerberg posted a photo on Friday that shows him jogging through Beijing's Tiananmen Square, on a day when air pollution levels were considered hazardously high. To many people, the gesture looked like yet another attempt to cajole leaders into unblocking Facebook in China, where the site has been banned since 2009.

It's great to be back in Beijing! I kicked off my visit with a run through Tiananmen Square, past the Forbidden City and...

According to the Guardian, Beijing smog was 15 times the amount the World Health Organization considers safe; at levels that high, people are warned against engaging in outdoor activities. Chinese media outlets were quick to comment on Zuckerberg's run—deeming it an obvious appeal to Chinese officials—and note that he wasn't wearing a protective mask.

"How far would you go to curry favor with China?" the Beijinger wrote. "How about running through Tiananmen Square without a mask in this morning’s thick-as-pea-soup AQI 337 air?"

Zuckerberg, who is in Beijing for this year's China Development Forum, was criticized on social media too, with some users pointing out that he had jogged through the same place where the Tiananmen Square massacre took place, which killed hundreds—and potentially thousands—of people in 1989.

The CEO has repeatedly expressed his interest in China, even going so far as to deliver a full speech in Mandarin to university students last year; Zuckerberg has been learning the language since 2010 to better communicate with his wife's grandmother.